Field of the Invention
The present invention relates to a gripper assembly for clamping a sheet material article such as a newspaper, a newspaper insert, a plurality of sheets or signatures, a magazine or the like that is to be transported by the gripper assembly.
Gripper systems are typically utilized by newspaper publishers for conveying newspapers, inserts or a plurality of sheets or signatures, hereinafter referred to as books, from one location to another. A gripper of that kind is known, for example, from European patent document EP 0 546 512 which describes a gripper assembly for clamping articles. The gripper assembly according to this document has a first and second clamp member where the second clamp member is able to pivot relative to the first clamp member where a coil or compression spring is compressed when the second clamp member is in its open position. To hold the second clamp member in the closed position it is necessary to provide a latch means. This latch means must be able to resist the torque that results from the entire clamp force. This configuration, however, suffers from its relatively inefficient clamping force. Furthermore, it is difficult to custom tailor grippers to specific applications and to create matched springs between right-hand and left-hand sides of the gripper.